staging: wilc1000: fix memdup.cocci warnings

drivers/staging/wilc1000/host_interface.c:946:32-39: WARNING opportunity for kmemdup
drivers/staging/wilc1000/host_interface.c:970:30-37: WARNING opportunity for kmemdup

 Use kmemdup rather than duplicating its implementation

Generated by: scripts/coccinelle/api/memdup.cocci

Fixes: aaea2164 ("staging: wilc1000: check for kmalloc allocation failures")
CC: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Julia Lawall <julia.lawall@lip6.fr>
Reviewed-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>